Data from: Relative costs of offspring sex and offspring survival in a polygynous mammal

Costs of reproduction are expected to be ubiquitous in wild animal populations and understanding the drivers of variation in these costs is an important aspect of life-history evolution theory. We use a 43 year dataset from a wild population of red deer to examine the relative importance of two factors that influence the costs of reproduction to mothers, and to test whether these costs vary with changing ecological conditions. Like previous studies, our analyses indicate fitness costs of lactation: mothers whose calves survived the summer subsequently showed lower survival and fecundity than those whose calves died soon after birth, accounting for 5% and 14% of the variation in mothers' survival and fecundity, respectively. The production of a male calf depressed maternal survival and fecundity more than production of a female, but accounted for less than 1% of the variation in either fitness component. There was no evidence for any change in the effect of calf survival or sex with increasing population density.

繁殖成本被认为广泛存在于野生动物种群中，解析这类成本的变异驱动因子，是生活史进化理论的重要研究方向之一。本研究依托一项覆盖43年的野生马鹿种群数据集，探究影响母体繁殖成本的两类因素的相对重要性，并检验这些繁殖成本是否随生态环境变化而发生改变。与既往研究一致，本研究的分析结果显示哺乳存在适合度成本：幼鹿成功度过夏季的母鹿，其后续存活率与繁殖力均低于幼鹿出生后不久即死亡的母鹿；该效应分别解释了母体存活率与繁殖力变异的5%和14%。产下雄性幼鹿对母体存活率与繁殖力的抑制作用强于产下雌性幼鹿，但该效应仅能解释两类适合度指标变异的1%以内。未发现幼鹿存活率或幼鹿性别对繁殖成本的影响随种群密度升高而发生改变的证据。